1. Field of the Invention
The present invention relates to an electrostatic motor utilizing static electricity as a drive force.
2. Description of the Related Art
An electrostatic motor, as described in Japanese Unexamined Patent Publication No. 6-78566 etc., has a stator film electrode and a slider film electrode The stator film electrode and the slider film electrode have a multiphase AC power supply connected to them. The slider film electrode is made to slide relative to the stator film electrode.
A conventional electric motor using electromagnetic force requires a magnetic coil, permanent magnets, or other members for generating magnetic force and is difficult to make compact. However, an electrostatic motor does not require a magnetic coil, permanent magnets, or other large mass elements, so can be made ultrasmall and can be utilized as a source of drive power for micromachines etc.
FIG. 20 is a schematic perspective view of a linear electrostatic motor. A stator film electrode 1 has different phase electrode elements 3 formed by copper foil or other conductive strip-shaped thin films or thin wires etc. buried in an insulator 4. Similarly, a slider film electrode 2 has similar electrode elements 3 buried in an insulator 4. The stator film electrode 1 and the slider film electrode 2 have the different phase terminals connected to different phase outputs of a multiphase AC power supply and are made to generate a traveling wave field, which makes the slider film electrode 2 move linearly with respect to the stator film electrode 1. To make a linear electrostatic motor generate a larger force, the linear electrostatic motor may be constructed by stacking a plurality of sets of stator film electrodes 1 and slider film electrodes 2.
In the case of a rotary electrostatic motor, as shown by the schematic perspective view of FIG. 21, a stator film electrode 1 has different phase electrode elements 3 formed by conductive strip-shaped thin films or thin wires etc. buried in a radial array in an insulator 4. Similarly, a slider film electrode 2 also has different phase electrode elements 3 buried in a radial array in an insulator 4. This rotary electrostatic motor differs from the linear electrostatic motor shown in FIG. 20 only in the point that the different phase electrode elements 3 are arranged radially. The rest of the configuration is the same as that of the linear electrostatic motor. Corresponding elements are assigned the same reference numerals. In this rotary electrostatic motor as well, the stator film electrode 1 and the slider film electrode 2 are connected to a multiphase AC power supply and are made to generate a traveling wave field, which makes the slider rotate relative to the stator.
In the case of this rotary electrostatic motor as well, to generate a larger force, the rotary electrostatic motor may be constructed by stacking a plurality of sets of stator film electrodes 1 and slider film electrodes 2 and connecting the stator film electrodes 1 and the slider film electrodes 2 with each other.
FIGS. 22A to 22C are views for explaining the film electrodes forming the stator and slider film electrodes 1, 2. FIG. 22A is a view of one surface (front surface) of a film electrode 1 or 2 as seen head-on, while FIG. 22B is a view of the other surface (back surface) as seen head-on. These show the electrode elements and the patterns of the power feed paths for feeding power to the electrode elements. The electrode elements and power feed paths shown by the solid lines are positioned at the viewed sides, while the electrode elements and power feed paths shown by the broken lines are positioned at the opposite sides.
Further, FIG. 22C is a sectional view taken along the line A–A′ of FIG. 22A. Each of the stator and slider film electrodes 1, 2 has different phase electrode elements 3 formed by conductive strip-shaped thin films or thin wires etc. buried in an insulator 4. FIGS. 22A to 22C show as an example a film electrode 1 or 2 driven by a three-phase AC power supply. The film electrode 1 or 2 is provided with plated through hole conductive parts 6a, 6b, 6c connected to the first, second, and third phase outputs of the three-phase AC power supply. The through hole conductive part 6a connected to the first phase output is connected through the power feed path 5a to the first phase electrode elements 3a, 3a . . . , while similarly the through hole conductive part 6b connected to the second phase output is connected through the power feed path 5b to the second phase electrode elements 3b, 3b . . . and the through hole conductive part 6c connected to the third phase output is connected through the power feed path 5c to the third phase electrode elements 3c, 3c. . . The second phase power feed path 5b is arranged at the opposite side (back surface) from the side where the other phase power feed paths 5a, 5c and the electrode elements 3a to 3c are provided and is connected with the second phase electrode elements 5b, 3b through the through hole conductive parts 7, in order to prevent its intersecting with and contacting the other phase power feed paths 5a, 5c. 
As shown in FIG. 22C as a cross-sectional view taken along the line A–A′, two insulator films forming base films 4a are bonded back-to-back with each other. A conductor layer is bonded to one of the base films 4a and etched to form a pattern of the conductor of the power feed path 5b on the base film 4a. Another conductor layer is also bonded to the other of the base films 4a and etched to form patterns of the conductors of the electrode elements 3a, 3b, 3c and the power feed paths 5a, 5c on the other base film 4a. The outsides are covered by cover films 4b which form insulating layers. That is, the film electrode 1 or 2 is formed by a layer of the cover film 4b, a layer of the power feed path 5a and an adhesive, a layer of one base film 4a, a layer of an adhesive, a layer of the other base film 4a, a layer of the electrode elements 3a, 3b, 3c, the power feed paths 5a and 5c and the adhesive, and a layer of the cover film 4b. 
Power is fed through the different phase through hole conductive parts 6a, 6b, 6c connected to the different phase outputs of the multiphase AC power supply (in the example shown in the drawings, a three-phase AC power supply) to the stator film electrode 1 and the slider film electrode 2 to generate a traveling wave field, which causes the slider film electrode 2 to slide with respect to the stator film electrode 1.
FIG. 23 to FIG. 28 are views for explaining an assembly process and stacking process of such a stator film electrode 1 or slider film electrode 2.
First, as shown in FIG. 23, a base film 4a is formed with through holes, then the through holes are plated to form conductive parts 6a′ to 6c′ and 7 for connecting the different phase electrode elements 3a to 3c and the AC power supply with each other. The strip-shaped thin films comprised of copper foil or another electric conductor at the two sides of the base film 4a are etched etc. to form patterns for forming the electrode elements 3 (3a to 3c) and the power feed paths 5a to 5c. Next, cover films 4b, 4b are bonded by an adhesive to the two surfaces of the base film 4a, on which the electrode elements 3 etc. are provided, thereby forming a stator or slider film electrode 1 or 2. Note that the cover films 4b, 4b are formed with through hole conductive parts 6a″, 6b41 , 6c″ facing the through hole conductive parts 6a, 6b, 6c for connecting to the power supply.
Next, as shown in FIG. 24 and FIG. 25, spacer members 10 are arranged at the ends of the stator film electrode 1 and the slider film electrode 2 (see FIG. 25 and FIG. 26) and the effective drive surfaces of the stator film electrode 1 and the slider film electrode 2 on which the electrode elements 3 are arranged in parallel are arranged to face each other (FIG. 27) so that the through hole conductive parts 6a to 6c (conductive parts formed by the conductive parts 6a′ to 6c′ and 6a″, 6b″, 6c″) of the stator film electrode 1 and the slider film electrode 2 and through holes 10a, 10b, 10c provided at the spacer members 10 are aligned with each other. Thus, an electrostatic motor is formed by a set of a stator film electrode 1 and a slider film electrode 2.
Further, when stacking a plurality of sets of stator film electrodes 1 and slider film electrodes 2, as shown in FIG. 28A, the sets of the stator film electrodes 1 and slider film electrodes 2 are positioned and successively stacked (FIGS. 28A and 28B show the example of providing two sets of stator film electrodes 1 and slider film electrodes 2 for forming a single unit of an electrostatic motor) and conductive pins 11 (11a to 11c) are inserted through the through hole conductive parts 6a to 6c for connecting to the power supply. Conductive pins 11 (11a to 11c) of the stator film electrodes 1 are connected to the stator AC power supply, while conductive pins 11 (11a to 11c) of the slider film electrodes 2 are connected to the slider AC power supply, whereby power is supplied through the conductive pins 11, the conductors of the through hole conductive parts 6a to 6c, the power feed paths 5a to 5c, and the power feed through hole conductive parts 7 to the different phase electrode elements 3a to 3c of the stator film electrodes 1 and slider film electrodes 2.
FIG. 28B shows an embodiment in which instead of the conductive pins 11, conductive rubber or conductive metal spring or other connection parts 12 are used to feed power to the electrode elements 3 of the stacked stator film electrodes 1 and the slider film electrodes 2. These connection parts are inserted in the through hole conductive parts 10a, 10b, 10c of the spacer members 10 and made to abut against or engage with the through hole conductive parts 6a to 6c of the stator film electrodes 1 and the slider film electrodes 2 at their tips.
After plurality of stator film electrodes 1 and slider film electrodes 2 are stacked in this way, the stator film electrodes 1 are fastened to a stator housing and the slider film electrodes 2 are fastened to a slider housing. Thus, a plurality of unit electrostatic motors are stacked to obtain an electrostatic motor comprised of multiple units.
Note that in FIGS. 23, 24, and 26, for convenience in illustration, the cover films 4b are illustrated as if they were transparent members.
In the above conventional electrostatic motor, the stator film electrode 1, the slider film electrode 2, and the spacer members 10 are arranged at predetermined positions to form a set, a plurality of such sets of stator film electrodes 1, slider film electrodes 2, and spacer members 10 are stacked, conductive pins 11 or connection parts 12 are used to electrically connect the stator film electrodes 1 and the slider film electrodes 2, and the stator film electrodes 1 and slider film electrodes 2 are fastened to housings.
However, the stator and slider film electrodes 1, 2, as explained above, are mainly formed by base films 4a and cover films 4b and therefore are extremely thin (thicknesses of tens of micrometers), so if even a slight force acts on the film electrodes 1, 2, they will end up changing in positions and orientations. This makes it extremely difficult to align and assemble the stator and slider film electrodes 1, 2 and the spacer members 10 all at once.